In an article published in Current Biology, Prof. Talila Volk of the Weizmann Institute's Molecular Genetics Department has revealed a series of interactions between proteins that serves to maintain order in the early stages of embryonic development. The "cop" is a fruit fly protein named HOW, and it works by "arresting" strands of RNA on their way to manufacture a second protein. Levels of the second protein, known as Cdc25, regulate the timing of cell division, and its production is ultimately controlled by yet another protein, Twist, which sets the process in motion. In this intricately choreographed scenario, cells invaginate from the outer layer of the nascent embryo into its interior, changing shape as they go. These cells form the mesoderm or "in-between layer," which eventually gives rise to muscle and other internal tissues. At the same time, Twist prompts the Cdc25 gene to step up activity, as well as activating the production of HOW. HOW then takes direct action against Cdc25 RNA by breaking it apart, leading to the arrest of cell division during mesoderm invagination.
When Volk and her team studied the newly-formed embryos of mutant fruit flies that lacked the gene for HOW, they found the timing for this early developmental stage was skewed. Cells divided to excess while the inward migration of the mesoderm-bound cells was delayed.
Once mesoderm formation is co
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American Committee for the Weizmann Institute of Science